Update rexml requirement from = 3.1.7.3 to = 3.3.8

---
updated-dependencies:
- dependency-name: rexml
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

next_rails.gemspec

@@ -29,6 +29,6 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency "simplecov", "~> 0.17.1"
   spec.add_development_dependency "timecop", "~> 0.9.1"
   spec.add_development_dependency "byebug"
-  spec.add_development_dependency "rexml", "3.1.7.3" # limited on purpose, new versions don't work with old rubies
+  spec.add_development_dependency "rexml", "3.3.8" # limited on purpose, new versions don't work with old rubies
   spec.add_development_dependency "webmock", "3.16.2" # limited on purpose, new versions don't work with old rubies
 end